The external accessory PMA 50 has been specially developed for Polarization Modulation measurements. It can be adapted to Bruker INVENIO and VERTEX FTIR spectrometers. All optic and electronic components in the PMA 50 module are optimized for the Polarization Modulation. Both linear dichroitic measurement techniques like PM-IRRAS and circular dichroitic experiments like VCD spectroscopy can be realized using this dedicated system. 
 
The core of the Polarization Modulation technique is the Photoelastic Modulator (PEM) with a nominal modulation frequency of 42 kHz. With the help of the parallel 24-bit dual-channel data acquisition technology the sum and the difference signals can be collected simultaneously with highest sensitivity. The PMA 50 module exhibits short beam path, and therefore provides optimal S/N ratio and stability. 
 
In combination with optical filters and the automated software controllable internal aperture in INVENIO and VERTEX spectrometers the signal quality can be further optimized with respect to the desired spectral range and sample size. To reach the highest performance in Polarization Modulated Applications, the polarized light is focused on the detector element by a lens providing that only non-polarizing optical components are used after polarization.